Given by: Dr. Robert Sayre
Rapid Precision Testing Laboratories
Wednesday, February 20, 2008
4:00pm in Manning Hall room 201
Refreshments will be served at 3:30pm in Manning Hall room 222
Submitted to the FDA in December 2007
Docket: 1978N-0038 - Sunscreen Drug Products for Over-the-Counter Human Use; Proposed
Amendment of Final Monograph. Comment on UVA Solar Simulator for Sunscreen Testing.
The currently proposed solar simulator for UVA sunscreen testing has been described
as having too little UVA-1. The proposed FDA standard will perpetuate this problem
causing the UVA protection of sunscreen products to be over estimated and thereby
misrepresent sunscreen products actual protection in sunlight.
Representative UVA solar simulators meeting the proposed FDA standard at either end
of the proposed spectral limit will produce UVA protection values from twice to three
times greater than the UVA protection actually provided against natural sunlight.We
propose that the UVA spectral region (320-400 nm) of the CIE Air Mass 1.0 solar reference
spectrum be adopted as the FDA standard for UVA solar simulators.
Goodness of Fit Indices for the persistent pigment darkening (PPD) effectiveness of
sunlight at different solar zenith angles ranges from ~93% -100% relative to the standard
CIE Air Mass 1 solar spectrum. The current UVA filtered solar simulators have PPD
Goodness of Fit Indices of less than 80%. We propose that solar simulators for UVA
sunscreen testing would be deemed to comply with the standard if their PPD effective
Goodness of Fit Index exceeded 90%.
We have determined that a xenon arc source filtered with a simple idealized dichroic
band pass filter, passing a band of UVA from 320 to 400 nm and blocking visible and
shorter UV outside this band, produces a UVA solar simulator with a Goodness of Fit
Index for PPD effective irradiance of ~94%. Comparison of our proposed UVA solar simulators
cumulative effective spectrum to those of CIE Air Mass 1.0, 1.5 & 2.0 solar spectra
shows that throughout a broad range of solar angles the UVA spectral effectiveness
distribution is comparable.
This means that the PFA for a sunscreen product in a laboratory clinical test will
be predictive of UVA protection afforded consumers, using the sunscreen product as
prescribed, outdoors under normally varying solar angle sunlight. This clearly suggests
that the human laboratory clinical test does not need to be compared to an investigatory
in vitro test which does not apply the product to individual volunteers and test there
response to exposure.